About the Flag

The municipality of Arco-Íris (lit., Rainbow; 1,925 inhabitants in
2010; 26,321 ha) is located in northwestern São Paulo State.

Arco-Íris was founded in 1928 by João Florenço, originating from
Glicério, northwestern São Paulo State. He cleared the forest to grow
grain crops and was quickly joined by other pioneers, including
Aurélio Moreno Zamora and José Morábito. Aurélio Moreno Zamora
established Vila Santa Helena and set up a sawmill to exploit the
local resources in timberwood. The district of Arco-Íris was
established by State Law No. 233 of 24 December 1948, as part of the
municipality of Tupã, and inaugurated on 1 January 1949.
The municipality of Arco-Íris was established by State Law No. 8,550
of 30 December 1993 and inaugurated on 1 January 1997. http://www.arcoiris.sp.gov.br - Municipal website

The flag of Arco-Íris is presented on Wikimedia Commons as blue with
four white-green-red-yellow diagonal stripes, a native's headdress in
lower hoist and a cross patty in upper hoist, the two argent. This is
a banner of the municipal arms, on which the stripes are bowed and not
straightforward.

The image was contributed on 3 February 2013 by "Prefeitura
Municipal", quoting the official municipal website as the source. No
other source for the flag was found.
Several municipal flags have been recently uploaded with the same
credit, although, in most cases, the matching municipal website does
not show the flag. However, photos of the flags, when available,
indicate that the accuracy of these submissions is quite high (except
the 2:3 proportions that do not match the common use of 14:20
proportions).
http://commons.wikimedia.org/wiki/File:Bandeira_Arealva.pngIvan Sache, 11 March 2013